Many new and existing golf courses have narrowed their fairways and expanded their rough areas on either end of the fairways. Roughs requires less care than fairways, so narrowing the fairways allows golf course operators to lower their maintenance costs. For example, irrigation requirements may be reduced if only the fairways are watered. If grasses in the roughs are allowed to grow longer, those non-irrigated areas are less brown. Trees and other aesthetic features may be located in the roughs, because roots and shade can inhibit turf growth in the fairways.
Golf course roughs must be maintained regularly using grass mowing machines that can mow the vegetation at an acceptable length and appearance. Equipment for mowing golf course roughs typically includes a traction vehicle carrying three or five rotary cutting units, each rotary cutting unit mounted on the end of a lift arm extending from the traction vehicle. A rotary cutting unit includes a cutting blade mounted to the lower end of a spindle rotated by a hydraulic motor. The lift effect of the cutting blade may help stand up the grass to provide high cut quality by the blade's cutting edge. The rotary cutting unit may be rear discharge to allow for optimal clipping dispersal and easy trimming using either the left-front or right-front unit. A rear discharge opening may be provided through a lower portion of the wall of the cutting chamber or shell.
Some rotary cutting units have features within the cutting chamber that are intended to move or deflect clippings downwardly for mulching or discharge. For example, U.S. Pat. No. 4,189,903 relates to a rotary lawn mower with a removable mulching attachment that directs clippings inwardly toward the center of the unit where they pass downwardly through the plane of the blade. U.S. Pat. No. 5,638,667 relates to a mulching mower with a wedge-shaped extension that is sloped downwardly as it extends radially outwardly. U.S. Pat. No. 6,470,663 relates to a rotary cutting unit with a spiral ramp to progressively force clippings down. As the blade rotates in the direction of the spiral, the clippings and air are pushed out of the cutting chamber through the rear outlet. U.S. Pat. Nos. 6,990,793 and 7,055,301 relate to a variable mulching system for a rotary cutting unit that is designed to help move clippings downwardly for mulching or to a discharge outlet.
Conventional deflection baffles can reduce the lift effect of the cutting blade because the grass clippings and air are pushed outwardly above the blade's cutting edge. This can result in an undesirable laying down and rolling over effect on the grass. This also can result in a high stress pressure point on the tip of the blade, which may contribute to loosening of the blade from the spindle, cracking or excess vibration.
Additionally, conventional deflection baffles may cause clippings or other material to collect and compact in areas under the cutting unit, while it is in either an open discharge position or mulching position. Clippings or other material that accumulates in the cutting chamber can decrease the blade lift and cause pressure on the top of the blade, preventing the clippings from being processed properly. This can slow the blade rotation and/or reduce cut quality, especially in heavy cutting conditions where large amounts of material are being cut.
A rotary cutting unit is needed having a deflection baffle that keeps the clippings flowing in a manner that does not restrict or compromise the performance of the unit, does not counteract the lift provided by the cutting blade, and does not cause undesirable stress and/or strain to the components of the system including the blade and joint. There is a need for a rotary cutting unit with a deflection baffle that can help stand up the grass, minimize stress to the blade tip, and that will not contribute to loosening of the blade from the spindle, cracking or excess vibration.